In the oil industry, there are two measurements which are of concern when attempting to determine oil produced by an oil well. The first being is the gross production of the oil well and the second is the percentage of oil content in gross production.
In order to determine gross production, it is conventional to employ a "paddle wheel" mechanism in the well production flow stream. The rotational velocity of the paddle is monitored and used in calculation to obtain a gross production figure.
In order to determine the percentage oil content from the gross production, it was conventional to manually sample the well production; however, in recent years automated systems have been developed to facilitate this process. Some known systems use a test vessel in which a constant volume of liquid is admitted and monitored by a float arrangement. The test vessel is mounted on a monitoring mechanism calibrated according to the density of water. The difference in output between a predetermined volume of water and an equal volume of well production is a measure of the percentage oil content of the well output. Other automated systems use a probe to detect the changes in the oil-water ratio by means of a "dielectric constant" effect.
Heavy oil has a solids content often in excess of 15% and is of a much greater viscosity than conventional oil. The above described measurement systems suffer from significant drawbacks. For example, the paddle wheel arrangement tends to become clogged with heavy oil. The constituent elements of the heavy oil tend to stratify in the sample container giving different results depending upon the depth from which a sample is taken. Further, all known automated systems require some form of solids filtration. It is not practical to filter solids out of heavy oil production, the heavy oil will either not flow through or will rapidly destroy any known filtration mechanism. In addition, the build up of solids upon any test probe or testing vessel used will, over time, inevitably result in a distortion of the data obtained.